This list of top downloaded iPhone apps shows why Twitter is ripe for an acquisition

It's no surprise that the "Big Four" tech companies — Facebook, Google, Microsoft and Apple — have dominated the top application downloads for iOS for the past five years.

Twitter's inclusion at number nine on App Annie's list, the only app on the list not owned by one of the big four companies, shows why Twitter could make an attractive acquisition target.

It's already been rumored that both Facebook and Google have approached the company about buying it out. Google purchasing the company would not only benefit its search and social ambitions, but also increase its foothold on iOS. Facebook, which owns four of the top apps including its eponymous social network, is all about its advertising business and Twitter would be another popular-enough option that would appeal to advertisers.